JP6965018B2 - Wafer processing method - Google Patents

Description

The present invention relates to a method for processing a wafer that forms a gettering layer on the wafer.

In the semiconductor device manufacturing process, a semiconductor device is formed by dividing a semiconductor wafer on which a plurality of devices are formed along a street. In order to reduce the size and weight of the semiconductor device, the back surface of the semiconductor wafer is ground before the semiconductor wafer is divided. When the semiconductor wafer is ground in this way, a grinding strain layer of about 1 μm composed of microcracks is generated on the back surface of the semiconductor wafer. When the thickness of the semiconductor wafer is reduced to 100 μm or less, there is a problem that the bending strength of the semiconductor device is lowered due to this grinding strain layer.

In order to solve such a problem, after grinding the semiconductor wafer to a predetermined thickness, the back surface of the semiconductor wafer is subjected to polishing, wet etching, dry etching, etc., and the grinding strain generated on the back surface of the semiconductor wafer is generated. The layer is removed to prevent a decrease in the bending strength of the semiconductor device.

On the other hand, in a semiconductor wafer in which a plurality of semiconductor devices having a memory function are formed such as a DRAM and a flash memory, there is a problem that the memory function is deteriorated when the grinding strain layer is removed. This is because the gettering effect disappears when the grinding strain layer on the back surface of the semiconductor wafer is removed, and metal ions such as copper contained inside the semiconductor wafer float on the surface side where the device is formed, resulting in current leakage. Is thought to occur.

In order to solve such a problem, a polishing pad for forming a gettering layer composed of microcracks having a thickness of 0.2 μm or less has been proposed on the back surface of the semiconductor wafer (see, for example, Patent Document 1). .. The polishing pad of Patent Document 1 is a liquid in which solid-phase reaction fine particles (abrasive grains for polishing) that induce a solid-phase reaction with silicon and fine particles for gettering (abrasive grains for gettering) having a higher Mohs hardness than silicon are mixed. It is constructed by impregnating a non-woven fabric with a binder. With this polishing pad, the grinding strain layer due to the grinding wheel remaining on the back surface of the semiconductor wafer can be removed, and a slight scratch that does not reduce the bending strength can be formed on the back surface of the semiconductor wafer to form a gettering layer. .. This makes it possible to manufacture a semiconductor wafer having a gettering effect.

JP-A-2015-46550

By the way, crystal defects in the silicon substrate constituting the wafer have the same effect as the gettering effect. Therefore, when there are many crystal defects in the silicon substrate, the silicon substrate has a gettering effect to some extent, so that the gettering layer formed may be thinner than in the case where there are few crystal defects. On the other hand, in the case of a high-purity wafer having few crystal defects on the silicon substrate, it is necessary to form the gettering layer thicker than in the case of many crystal defects. Therefore, when a polishing pad containing a predetermined amount of gettering abrasive grains described in Patent Document 1 is used, a high-purity wafer having few crystal defects has many crystal defects because the gettering layer is formed thickly. There is a problem that the processing time is longer than that of a wafer and it takes a long time to form the gettering layer.

The present invention has been made in view of the above points, and one object of the present invention is to provide a processing method for a wafer capable of forming a gettering layer under appropriate processing conditions according to the type and thickness of the wafer.

The method for processing a wafer according to one aspect of the present invention is a method for processing a wafer in which a gettering layer that regulates the induction of metal ions is formed on the back surface of the wafer in which a device is formed on the surface of a silicon substrate. A wafer holding step of attaching a protective member to the polishing pad to hold the protective member side on the holding surface of the chuck table, and a solid phase that induces a solid phase reaction with silicon while supplying an alkaline solution having a pH of 10 or more and 12 or less to the polishing pad. A strain layer removing step of removing a strain layer from the back surface of a wafer by polishing the back surface of the wafer with the polishing pad while rotating a polishing pad obtained by impregnating a non-woven fabric with reaction fine particles and drying the chuck table, and strain. After performing the layer removal step, the polishing pad is rotated while the supply of the alkaline solution is stopped and the polishing pad is supplied with fine particles for gettering that have a higher moth hardness than pure water and silicon and form a gettering layer on the polishing surface. Before performing the gettering layer forming step, including a gettering layer forming step of forming a gettering layer by scratching the back surface by polishing the back surface of the wafer with a polishing pad while rotating the chuck table. in the wafer type and / or wafer particle size and the supply amount of the gettering fine particles based on the thickness information is stored for each wafer ID in the control unit, the gettering layer forming step includes a crystal defect of each wafer, control supplied by controlling the particle径及beauty supply amount of the fine particles for gettering according to wafer ID by parts.

According to these configurations, the particle size and / or the supply amount of the gettering fine particles can be controlled according to the state and thickness of the crystal defects of the wafer. As a result, the gettering layer can be formed under appropriate processing conditions according to the type of wafer. Therefore, a gettering layer having an appropriate thickness can be formed on the wafer, and the processing time of the wafer can be shortened.

According to the present invention, a gettering layer can be formed under appropriate processing conditions according to the type and thickness of the wafer.

It is a perspective view of the polishing apparatus which concerns on this embodiment. It is a figure which shows the supply system of the alkaline solution for polishing and the fine particle for gettering which concerns on this embodiment. It is a figure which shows the wafer holding process which concerns on this embodiment. It is a figure which shows the strain layer removing process and the gettering layer forming process which concerns on this embodiment.

Hereinafter, the polishing apparatus will be described with reference to the attached drawings. FIG. 1 is a perspective view of the polishing apparatus according to the present embodiment. The polishing apparatus according to the present embodiment is not limited to the dedicated polishing apparatus as shown in FIG. 1, and is, for example, a fully automatic type in which a series of processing such as grinding, polishing, and cleaning is performed fully automatically. It may be incorporated in a processing apparatus.

As shown in FIG. 1, the polishing apparatus 1 is configured to polish the wafer W by chemical mechanical polishing (CMP) using a polishing pad 47 described later. The wafer W is made of a silicon wafer, and a plurality of streets are formed in a grid pattern on the surface W1, and devices (not shown) such as ICs and LSIs are formed in a region partitioned by the streets. When the back surface W2 of the wafer W is ground to a predetermined thickness (for example, 100 μm), a protective tape as a protective member is provided on the surface W1 of the wafer W in order to protect the device formed on the surface W1 of the wafer W. T is pasted. The wafer W is held on a chuck table 21 described later with the back surface W2, which is the surface to be processed, facing upward.

A rectangular opening extending in the Y-axis direction is formed on the upper surface of the base 11 of the polishing apparatus 1, and this opening is covered with a table cover 12 and a bellows-shaped waterproof cover 13 that can move together with the chuck table 21. ing. Below the waterproof cover 13, a moving means 24 for moving the chuck table 21 in the Y-axis direction and a rotating means 22 for continuously rotating the chuck table 21 are provided. A holding surface 23 for holding the wafer W is formed on the surface of the chuck table 21 via a protective tape T by a porous porous material. The holding surface 23 is connected to a suction source (not shown) through a flow path in the chuck table 21.

The moving means 24 has a pair of guide rails 51 arranged on the base 11 and parallel to the Y-axis direction, and a motor-driven Y-axis table 52 slidably installed on the pair of guide rails 51. There is. A nut portion (not shown) is formed on the back surface side of the Y-axis table 52, and a ball screw 53 is screwed into the nut portion. Then, the drive motor 54 connected to one end of the ball screw 53 is rotationally driven to move the chuck table 21 along the pair of guide rails 51 in the Y-axis direction. The rotating means 22 is provided on the Y-axis table 52, and supports the chuck table 21 so as to be rotatable around the Z-axis.

A column 14 is installed on the base 11, and the column 14 is provided with a processing feed means 31 for processing and feeding the polishing means 41 in the Z-axis direction. The machining feed means 31 has a pair of guide rails 32 arranged in the column 14 parallel to the Z-axis direction, and a motor-driven Z-axis table 33 slidably installed on the pair of guide rails 32. .. A nut portion (not shown) is formed on the back surface side of the Z-axis table 33, and a ball screw 34 is screwed into the nut portion. The ball screw 34 is rotationally driven by the drive motor 35 connected to one end of the ball screw 34, so that the polishing means 41 is machined and fed along the guide rail 32.

The polishing means 41 is attached to the front surface of the Z-axis table 33 via the housing 42, and is configured by providing a polishing pad 47 at the lower part of the spindle unit 43. A flange 45 is provided on the spindle unit 43, and the polishing means 41 is supported on the housing 42 via the flange 45. A mount 44 is attached to the lower part of the spindle unit 43, and a polishing tool 48 composed of a support base 46 and a polishing pad 47 is attached to the mount 44. The polishing means 41 is connected to a pipe for an alkaline solution for polishing and a pipe for fine particles for gettering. When the valve 65 is opened, the alkaline solution is supplied to the polishing means 41 as a polishing liquid, and when the valve 66 is opened, the gettering fine particles are supplied to the polishing means 41 as a polishing liquid.

The polishing device 1 is provided with a control unit 70 that controls each unit of the device in an integrated manner. The control unit 70 controls valves 65 and 66, and valves 67 and 68 described later. The control unit is composed of a processor, a memory, and the like that execute various processes. The memory is composed of one or a plurality of storage media such as ROM (Read Only Memory) and RAM (Random Access Memory) depending on the intended use. In the polishing apparatus 1 configured in this way, the polishing pad 47 is brought close to the wafer W held by the chuck table 21 while being rotated around the Z axis. Then, the polishing pad 47 is brought into rotational contact with the back surface W2 of the wafer W to polish the wafer W.

Here, the cutting strain layer generated by grinding the wafer is removed by polishing to prevent a decrease in the bending strength, but there is a problem that the gettering effect disappears when the cutting strain layer is removed. Therefore, the grinding strain layer of the wafer was removed by using a polishing pad containing the solid-phase reaction fine particles and the gettering fine particles, and the gettering layer was formed on the back surface of the wafer.

However, in a polishing pad containing solid phase reaction fine particles and gettering fine particles, in order to shorten the processing time for removing the grinding strain layer of the wafer, the ratio of the solid phase reaction fine particles fixed to the polishing pad is set. Need more. On the other hand, in order to shorten the processing time for forming the gettering layer on the wafer, it is necessary to increase the proportion of the gettering fine particles fixed to the polishing pad. Therefore, it may not be possible to shorten both the processing time for removing the grinding strain layer and forming the gettering layer.

In addition, the required thickness of the gettering layer differs depending on the crystal defects and thickness of the wafer. When the proportion of gettering fine particles fixed in the polishing pad is small, the wafer that needs to form a thick gettering layer has a problem that processing takes time. Therefore, in the present embodiment, the gettering layer is formed on the wafer under appropriate processing conditions by controlling the average particle size and / or the supply amount of the free gettering fine particles, and the wafer is formed. Reduce the processing time of.

First, with reference to FIG. 2, the supply system of the alkaline solution for polishing and the fine particles for gettering will be described in detail. FIG. 2 is a diagram showing a supply system of an alkaline solution for polishing and fine particles for gettering according to the present embodiment. A polishing pad 47 is attached to an annular support base 46 to form a polishing tool 48. The support base 46 is made of an aluminum alloy or the like, and a hole 46a through which the polishing liquid passes is opened in the central portion. The polishing pad 47 is formed in an annular shape and contains solid-phase reaction fine particles that induce a solid-phase reaction with silicon. Further, in the central portion of the polishing pad 47, a hole 47c communicating with the hole 46a formed in the support base 46 is opened.

The polishing pad 47 is formed by charging solid-phase reaction fine particles that induce a solid-phase reaction with a silicon wafer into a liquid binder and drying a non-woven fabric impregnated with the liquid binder. As the solid-phase reaction fine particles, SiO ₂ , CeO ₂ , ZrO _{2, and the} like are used, and the particle size of the solid-phase reaction fine particles is preferably, for example, 2 μm. Further, as the solid-phase reaction fine particles contained in the polishing pad 47, two or more types of solid-phase reaction fine particles can be used. Further, as the liquid binder, for example, a liquid in which urethane is dissolved in a solvent is used, and as the solvent, dimethylformamide, dimethyl sulfoxide, acetone, ethyl acetate and the like are used.

The polishing tool 48 configured in this way is mounted on the lower surface of the mount 44 attached to the lower end of the spindle unit 43. At this time, the flow path 43a formed at the center of the spindle unit 43 communicates with the holes 46a and 47c formed in the support base 46 and the polishing pad 47.

An alkaline solution supply source 61 for polishing and a pure water supply source 62 are connected to the flow path 43a of the spindle unit 43 via valves 65 and 66, respectively. In the middle of the pipe connecting the valve 66 and the pure water supply source 62, a gettering fine particle supply source A63 and a gettering fine particle supply source B64 are connected via valves 67 and 68, respectively. The alkaline solution of the alkaline solution supply source 61 for polishing or the fine particle supply source A63 for gettering and the fine particles A and B for gettering of the fine particle supply source B64 for gettering, which will be described later, are polished through the flow path 43a and the holes 46a and 47c. It is supplied to the pad 47.

The alkaline solution supply source 61 for polishing contains an alkaline solution. The alkaline solution in the polishing alkaline solution source 61 preferably has a pH of 10 or more and a pH of 12 or less. As the alkaline solution having a pH of 10 or more and a pH of 12 or less, TMAH (tetramethylammonium hydroxide), piperazine, potassium hydroxide, sodium hydroxide and the like are used.

The gettering fine particle supply source A63 and the gettering fine particle supply source B64 contain the gettering fine particles A and B having different average particle sizes in a state of being dispersed in pure water. The gettering fine particle source A63 contains, for example, a gettering fine particle A having an average particle size of 0.1 μm, and the gettering fine particle source B64 contains, for example, a gettering fine particle B having an average particle size of 1 μm. Is housed. Here, since the sizes of the gettering fine particles A and B are average particle sizes, the particle sizes of the fine particles vary.

The gettering fine particles A and B are fine particles having a Mohs hardness higher than that of silicon, and the Mohs hardness is preferably 9 or more. As the gettering fine particles, diamond, SiC, Al ₂ O ₃ , WC, TiN, TaC, ZrC, _{Al B, B 4} C and the like are used.

The control unit 70 controls the opening / closing and opening degree of the valves 65, 66, 67, 68 as described above. In the control unit 70, based on information such as crystal defects and thickness of each wafer W, the tank used as the gettering fine particle supply source A63 and the gettering fine particle supply source B64 for each wafer W for each wafer ID and for gettering. Information on the supply amounts of the fine particles A and B is stored in advance. By controlling the valves 67 and 68 based on this information, the control unit 70 switches the average particle size of the gettering fine particles A and B supplied to the polishing pad 47, and adjusts the supply amount.

When removing the cutting strain layer from the wafer, the valve 65 is opened by the control unit 70, and the alkaline solution is supplied from the polishing alkaline solution supply source 61 to the flow path 43a.

When forming the gettering layer on the wafer W, the control unit 70 opens the valve 66. At this time, the valve 67 or the valve 68 is opened, and the gettering fine particles A or the gettering fine particle supply B64 supply the gettering fine particles B from the gettering fine particle supply source A63. The gettering fine particles A and B are mixed with pure water supplied from the pure water supply source 62 in the pipe and supplied to the flow path 43a, respectively. Although the gettering fine particles A and B are configured to be mixed with pure water in the pipe, a mixing chamber may be provided in the pipe and mixed with pure water in the mixing chamber. As a result, the gettering fine particles A and B are uniformly mixed with pure water. The supply amount of the gettering fine particle A from the gettering fine particle supply source A63 and the gettering fine particle B from the gettering fine particle supply source B64 is determined by adjusting the opening degree of the valves 67 and 68 by the control unit 70. , Can be controlled.

By controlling the valves 67 and 68 with the control unit 70 in this way, the average particle size of the gettering fine particles A and B used for forming the gettering layer can be switched, and the supply amount can be adjusted. Therefore, the gettering layer can be formed under appropriate processing conditions according to the crystal defects and the thickness of the wafer W.

Hereinafter, the method of processing the wafer W according to the present embodiment will be described with reference to FIGS. 3 and 4. The processing method of the wafer W is a wafer holding step of holding the wafer W on the chuck table 21 and a strain layer removing step of polishing the back surface W2 of the wafer W with a polishing pad 47 while supplying an alkaline solution to remove the cutting strain layer. This includes a step of forming a gettering layer in which a polishing pad 47 is used to form scratches on the back surface W2 of the wafer W while supplying pure water and free gettering fine particles. FIG. 3 is a diagram showing a wafer holding step according to the present embodiment, and FIG. 4 is a diagram showing a strain layer removing step and a gettering layer forming step according to the present embodiment. FIG. 4A is a diagram showing a strain layer removing step, and FIGS. 4B and 4C are diagrams showing a gettering layer forming step.

As shown in FIG. 3, the wafer holding step is first carried out. The wafer W ground to a predetermined thickness is carried into the chuck table 21 with the front surface W1 to which the protective tape T is attached on the lower side and the back surface W2 on the upper side, and the wafer W is chucked through the protective tape T. It is held on the holding surface 23 of the table 21.

As shown in FIG. 4A, a strain layer removing step is performed after the wafer holding step. The chuck table 21 is moved below the polishing means 41 by the moving means 24 (see FIG. 1), and is positioned so that the rotation axis of the chuck table 21 and the rotation axis of the polishing pad 47 deviate from each other.

The chuck table 21 is rotated around the Z axis, and the polishing pad 47 is also rotated around the Z axis in the same direction as the chuck table 21. Then, the polishing pad 47 is processed and fed toward the back surface W2 of the wafer W by the processing feed means 31 (see FIG. 1) at ^{a polishing pressure of, for example, 300 g / cm 2} , and the polished surface of the polishing pad 47 is the entire back surface W2 of the wafer W. The wafer W is polished by rotational contact.

At this time, the valve 66 is closed, the valve 65 is opened, and the alkaline solution is supplied from the polishing alkaline solution supply source 61 to the flow path 43a in the spindle unit 43. As a result, the alkaline solution is supplied to the hole 47c formed in the polishing pad 47 through the hole 46a formed in the support base 46, for example, at a rate of 0.5 liter per minute. The alkaline solution spreads from the hole 47c of the polishing pad 47 to the polishing surface, and the wafer W is polished while the alkaline solution is supplied to the polishing pad 47. The polishing rate is set to, for example, 0.72 μm / min, and the polishing time is set to, for example, 2 minutes.

By carrying out the strain layer removing step in this way, the back surface W2 of the wafer W is polished by a predetermined amount and etched by the alkaline solution using the solid phase reaction fine particles contained in the polishing pad 47, so that the grinding process is performed. The grinding strain layer formed on the back surface W2 of the wafer W is removed.

As shown in FIG. 4B, a gettering layer forming step is performed after the strain layer removing step. The chuck table 21 is rotated around the Z axis, and the polishing pad 47 is also rotated around the Z axis in the same direction as the chuck table 21. Then, the polishing pad 47 is processed and fed toward the back surface W2 of the wafer W by the processing feed means 31 (see FIG. 1) at ^{a polishing pressure of, for example, 50 g / cm 2} , and the polished surface of the polishing pad 47 is rotationally contacted with the wafer W. Wafer W is polished.

At this time, the valve 65 is closed, the supply of the alkaline solution to the flow path 43a is stopped, the valve 66 is opened, the pure water from the pure water supply source 62, the fine particle supply source A63 for gettering, and the gettering. The supply of the gettering fine particles A and B from the fine particle supply source B64 is switched. The valve 67 or the valve 68 is opened, and the gettering fine particles A or the gettering fine particle supply B64 supply the gettering fine particles B from the gettering fine particle source A63. The gettering fine particles A and B are each mixed with pure water supplied from the pure water supply source 62 and supplied to the flow path 43a. As a result, pure water and gettering fine particles A or gettering fine particles B are supplied to the holes 47c formed in the polishing pad 47 via the holes 46a formed in the support base 46, and the pure water and gettering are provided. The fine particles A or the fine particles B for gettering spread from the holes 47c to the polished surface.

As shown in FIG. 4C, while the polishing pad 47 is supplied with pure water and the gettering fine particles A and B, the polishing pad 47 is in rotational contact with the wafer W by the moving means 24 (see FIG. 1). The chuck table 21 is moved in the direction of the arrow N. That is, while the back surface W2 of the wafer W is slid, the rotation axis of the chuck table 21 and the rotation axis of the polishing pad 47 are moved so as to be separated from each other in the Y-axis direction. The movement of the chuck table 21 in the direction indicated by the arrow N is carried out, for example, at a moving speed of 0.67 mm / sec for 1 minute, and the chuck table 21 is moved by about 40 mm. As a result, the back surface W2 of the wafer W is slightly scratched. By carrying out the gettering layer forming step in this way, the free gettering fine particles work strongly, and the gettering layer can be formed on the back surface W2 of the wafer W.

Here, for example, as shown in Table 1, the control unit 70 (see FIG. 2) supplies, for example, a gettering fine particle supply source A63 and a gettering fine particle supply for each wafer ID based on the information on the crystal defects of each wafer W. Information on the tank used as the source B64 and the supply amounts of the gettering fine particles A and B is stored. In Table 1, for example, wafer ID "A" has many crystal defects, wafer W, wafer ID "B" has fewer crystal defects than wafer ID "A", and wafer ID "C" has the fewest crystal defects. It shows a wafer W. Further, a <b.

In the gettering layer forming step, the control unit 70 controls the opening / closing and opening degree of the valves 67 and 68 based on this information. For example, in the case of the wafer W having the ID "A", the gettering fine particle supply source A63 is selected as the tank 1, the valve 67 is opened, and the gettering fine particle A is supplied to the polishing pad 47 a [g / l]. .. As a result, a gettering layer thinner than the wafer W of ID "C" is formed by using the gettering fine particles A having an average particle size smaller than that of the gettering fine particles B.

Further, for example, in the case of the wafer W of ID "B", the gettering fine particle supply source A63 is selected as the tank 1, the valve 67 is opened wider than in the case of the wafer W of ID "A", and the gettering fine particles A Is supplied to the polishing pad 47 in b [g / l]. As a result, the wafer W of ID "B" is polished in a state where the supply amount of the gettering fine particles A is larger than that of the wafer W of ID "A", so that the gettering layer is more than the wafer W of ID "A". Is formed thickly. By increasing the supply amount of the gettering fine particles A, the supply amount of the large particle size particles contained in the gettering fine particles A having an average particle size of 0.1 μm can be increased, so that the particle size is larger than 0.1 μm. The same effect as when a large gettering fine particle is used can be obtained. As a result, the processing speed of the wafer W is increased, and the time for forming the gettering layer having a predetermined thickness on the wafer W can be shortened.

Further, for example, in the case of the wafer W having the ID "C", the gettering fine particle supply source B64 is selected as the tank 2, the valve 68 is opened, and the gettering fine particle B supplies c [g / l] to the polishing pad 47. Will be done. As a result, a gettering layer thicker than the wafer W of ID "B" is formed by using the gettering fine particles B having an average particle size larger than that of the gettering fine particles A. Although the configuration for controlling the particle size and / or the supply amount of the gettering fine particles A and B according to the amount of crystal defects in the wafer W has been described, the gettering fine particles A and / or the supply amount are described. The configuration may be such that the particle size and / or the supply amount of B is controlled.

As described above, in the polishing apparatus 1, for example, the gettering fine particle supply source A63 and the gettering fine particle supply as the tanks 1 and 2 in which the gettering fine particles A and B having a plurality of types of average particle diameters are housed, respectively. A source B64 is provided and is connected to the flow path 43a via valves 67 and 68. In the gettering layer forming step, for example, tanks 1 and 2 to be used are selected by the control unit 70 for each wafer ID, and valves 67 and 68 are controlled to switch the average particle size of the gettering fine particles A and B. At the same time, the opening degree of the valves 67 and 68 is adjusted. As a result, the average particle size of the gettering fine particles A and B and / or the supply amount of the gettering fine particles A and B supplied from the tanks 1 and 2 used, depending on the state and thickness of the crystal defects of the wafer W. Can be controlled. Therefore, a gettering layer can be formed under appropriate processing conditions according to the type and thickness of the wafer W, and a gettering layer having an appropriate thickness can be formed on the wafer W. By controlling the average particle size and / or the supply amount of the gettering fine particles A and B, the gettering layer can be formed under appropriate processing conditions, so that the processing time of the wafer can be shortened.

As described above, in the processing method of the wafer W according to the present embodiment, the particle size and / or the supply amount of the gettering fine particles A and B can be controlled according to the state and the thickness of the crystal defects of the wafer W. As a result, the gettering layer can be formed under appropriate processing conditions according to the type of wafer W. Therefore, a gettering layer having an appropriate thickness can be formed on the wafer W, and the processing time of the wafer W can be shortened.

In the above embodiment, two types of gettering fine particles A and B having different average particle sizes are used, and two gettering fine particle supply sources A63 and a gettering fine particle supply source B64 are used in the polishing apparatus 1. The configuration is provided with valves 67 and 68, but the present invention is not limited to this. A plurality of types of gettering fine particles having different average particle sizes can be used depending on the crystal defects and thickness of the wafer W, and the polishing apparatus 1 may be provided with a plurality of gettering fine particle sources and valves. can.

Further, in the above embodiment, in the gettering layer forming step, the chuck table 21 is moved in the Y-axis direction by the moving means 24 (see FIGS. 1 and 4C), so that the back surface W2 of the wafer W is gettered. The structure is such that layers are formed, but the present invention is not limited to this. If the rotation axis of the chuck table 21 and the rotation axis of the polishing pad 47 are moved so as to be separated from each other while the back surface W2 of the wafer W is slid, the polishing pad 47 may be moved with respect to the chuck table 21. ..

Further, in the present embodiment, a polishing device for polishing a wafer has been described as an example of a processing device, but the present invention is not limited to this configuration. The present invention is applicable to other processing devices for polishing a wafer W while supplying particles. For example, it may be applied to a cutting device, a polishing device, a cleaning device, a cluster device combining these, and the like.

Moreover, although each embodiment of the present invention has been described, as another embodiment of the present invention, each of the above embodiments may be combined in whole or in part.

Moreover, the embodiment of the present invention is not limited to each of the above-described embodiments, and may be variously modified, replaced, or modified without departing from the spirit of the technical idea of the present invention. Furthermore, if the technical idea of the present invention can be realized in another way by the advancement of technology or another technology derived from it, it may be carried out by using that method. Therefore, the scope of claims covers all embodiments that may be included within the scope of the technical idea of the present invention.

In the present embodiment, the configuration in which the present invention is applied to a polishing apparatus for polishing a wafer has been described, but it is also possible to apply the present invention to a processing apparatus for processing a wafer W using a plurality of types of particles.

As described above, the present invention has an effect that a gettering layer can be formed under appropriate processing conditions according to the type and thickness of the wafer, and is particularly useful for a polishing apparatus for polishing a wafer.

1 Polishing device 21 Chuck table 23 Holding surface 46 Support base 47 Polishing pad 48 Polishing tool 61 Alkaline solution supply source for polishing 62 Pure water supply source 63 Fine particle supply source for gettering A
64 Gettering particle source B
65, 66, 67, 68 Valve 70 Control unit T Protective tape (protective member)
W Wafer W1 (Wafer) front side W2 (Wafer) back side

Claims (1)

It is a processing method of a wafer in which a gettering layer that regulates the induction of metal ions is formed on the back surface of a wafer in which a device is formed on the front surface of a silicon substrate.
A wafer holding process in which a protective member is attached to the surface of the wafer and the protective member side is held on the holding surface of the chuck table.
While supplying an alkaline solution having a pH of 10 or more and 12 or less to the polishing pad, the polishing pad obtained by impregnating a non-woven fabric with solid-phase reaction fine particles that induce a solid-phase reaction with silicon and drying the polishing pad is rotated and the chuck table is rotated. A strain layer removing step of removing the strain layer from the back surface of the wafer by polishing the back surface of the wafer with a polishing pad,
After performing the strain layer removing step, the supply of the alkaline solution is stopped, and while supplying the polishing pad with fine particles for gettering which have a higher moth hardness than pure water and silicon and form a gettering layer on the polished surface, It includes a gettering layer forming step of forming a gettering layer by scratching the back surface by polishing the back surface of the wafer with the polishing pad while rotating the polishing pad and rotating the chuck table.
Before carrying out the gettering layer forming step, the control unit stores the particle size and the supply amount of the gettering fine particles based on the wafer type and / or the wafer thickness information including the crystal defects of each wafer in the control unit. ,
The In the gettering layer forming step, the wafer processing method, characterized in that, to supply to control the particle径及beauty supply amount of gettering fine particles in accordance with the wafer ID by the control unit.

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